Methanol Weekly Topic: What should be the appropriate control level for the methanol circulation ratio? 2016.04.03--04.10
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This post was last edited by TH373637 on 2016-4-8 at 11:23. Methanol – Weekly topic: What are the appropriate values for the methanol circulation ratio and space velocity? What is the principle? April 3, 2016---April 10, 2016: The recycle ratio for shell-and-tube methanol synthesis towers is generally between 4 and 5. The recycle ratio of cold-jet methanol synthesis towers is generally between 8 and 10. Different types of synthesis towers have different circulation ratios, with each type having a ratio that is suitable for it. The most important factor is to control the ratio based on the principles of the reaction; the most reasonable ratio is the one that is best suited for the given situation. Ideally, a ratio of 2:1 should be achieved. If a lower space velocity is used, the reaction rate changes significantly. During the reaction, the composition of the gas mixture is closer to its equilibrium composition, resulting in a lower reaction rate and a lower production capacity of the catalyst. However, less gas is required per unit of methanol produced, which reduces the energy consumption associated with gas circulation. Additionally, less heat exchange area is needed to preheat the unreacted gas to the temperature at the catalyst inlet, and the temperature of the gas leaving the reactor is higher, allowing for better utilization of its thermal value. If a higher space velocity is used, the reaction rate changes little, and the catalyst production capacity increases; however, this increases the heat transfer area required for preheating, reducing the thermal energy utilization efficiency, which in turn increases the pressure drop and power consumption associated with the circulation of gas through the equipment ； Furthermore, the reduced concentration of reaction products in the gas increases the cost of separating them. Furthermore, once the air velocity increases to a certain level, the temperature of the catalytic bed cannot be maintained. In short, the optimal airspeed must be determined by taking into account the various factors mentioned above. In actual production, the space velocity (which, with a constant catalyst volume, depends on the amount of recycle gas) is one of the means used to control the temperature and yield of the synthesis tower; generally speaking, increasing the space velocity can boost the yield. Within the range of space velocity of 8000–10000 h-1, the space-time yield increases as the space velocity rises; beyond 10000 h-1, the effect of space velocity is minimal.
I asked this question yesterday; is there an answer? Can we communicate?
The recycle ratio of shell-and-tube methanol synthesis towers is generally between 4 and 5. The recycle ratio of cold-jet methanol synthesis towers is generally between 8 and 10.
In methanol production, the recycle ratio of shell-and-tube methanol synthesis towers is generally between 4 and 5, while that of counter-current methanol synthesis towers is generally between 8 and 10； The air velocity is generally maintained between 10,000 and 30,000 h-1.
This is closely related to the gas composition, tower type, catalyst, power machinery, and hydrogen recovery
What was said upstairs makes sense; there are quite a few influencing factors
What are the appropriate values for the methanol circulation ratio and space velocity? What is the principle? The recycle ratio of shell-and-tube methanol synthesis towers is generally between 4 and 5. The recycle ratio of cold-jet methanol synthesis towers is generally between 8 and 10. Different types of synthesis towers have different circulation ratios, with each type having a circulation ratio that is suitable for it. If a lower space velocity is used, the reaction rate changes significantly; the composition of the gas mixture during the reaction is closer to the equilibrium composition. The reaction rate is lower, and the catalyst utilization efficiency is reduced. However, less gas volume is required per unit of methanol produced, resulting in lower energy consumption for gas circulation. Less heat exchange area is needed to preheat the unreacted gas to the catalyst inlet temperature, and the temperature of the gas leaving the reactor is higher, allowing for a higher utilization of its thermal value. If a higher space velocity is used, the reaction rate changes little, and the catalyst production capacity increases; however, this increases the heat transfer area required for preheating, reducing the thermal energy utilization efficiency, which in turn increases the pressure drop and power consumption associated with the circulation of gas through the equipment ； Furthermore, the reduced concentration of reaction products in the gas increases the cost of separating them. Furthermore, once the air velocity increases to a certain level, the temperature of the catalytic bed cannot be maintained. In actual production, the space velocity (which, with a constant catalyst volume, depends on the amount of recycle gas) is one of the means used to control the temperature and yield of the synthesis tower; generally speaking, increasing the space velocity can boost the yield. Within the range of space velocity of 8000–10000 h-1, the space-time yield increases as the space velocity rises; beyond 10000 h-1, the effect of space velocity is minimal.
The circulation ratio is around 5! The air velocity is generally maintained between 10,000 and 30,000 h-1.
In methanol production, the recycle ratio of shell-and-tube synthesis towers is generally between 4 and 5； The recycle ratio of cold-jet synthesis towers is generally between 8 and 10 ； Its air velocity is generally controlled between 10,000 and 30,000 h-1.
One of the shell-and-tube synthesis towers in our plant has a recycle ratio of around 4–5, while another Cassart tower has a much lower recycle ratio, around 2–3.
The recycle ratio is directly related to the heat capacity of the methanol tower reactor as well as the catalyst conversion efficiency; under normal operating conditions, the recycle ratio for shell-and-tube towers ranges from 3.5 to 4.5, while it is said that the recycle ratio in the bedrooms tower at Hangzhou Linda can reach 2.0. However, this is not absolute; a comprehensive evaluation based on factors such as the composition of the feed gas and the reaction pressure is still required to select the appropriate reactor.